1. Field of the Invention
The present invention relates to a printer apparatus for a heat-sensitive adhesive sheet in which a heat-sensitive adhesive layer that is normally non-adhesive and exhibits adhesion only when heated is formed on one side of a sheet-like base material.
2. Description of the Related Art
Thermal activation sheets (print medium in which a coat layer containing a thermal activation component is formed on the surface, for example, heat-sensitive adhesive sheets) have recently become available as sheets to be applied to merchandises, and are used in wide fields. Examples of uses of thermal activation sheets include POS sheets for food products, delivery address sheets, sheets bearing medical information, baggage tags, and labels of bottles and cans.
Those heat-sensitive adhesive sheets are composed of a sheet-like base material (base paper, for example) one side of which has a heat-sensitive adhesive layer and the other side of which is a printable surface. The heat-sensitive adhesive layer is normally non-adhesive and exhibits adhesion when heated.
Heat-sensitive adhesives contain a thermoplastic resin, a solid plasticizer, or the like as a main constituent, and accordingly do not exhibit adhesive characteristics at normal temperatures. The heat-sensitive adhesives have property in which they become activated by heating with a thermal activation device, and exhibit adhesion. Activation temperatures are normally from 50 to 150° C. The solid plasticizer within the thermoplastic resin melts in this temperature range, and imparts adhesion to the thermoplastic resin. The melted solid plasticizer then gradually crystallizes via a supercooled state. Accordingly, the adhesive characteristics persist for a predetermined period of time. The heat-sensitive adhesive is applied to a surface of an object such as a glass bottle during the period where the adhesion is kept.
A “Linerless Label Printer” disclosed in JP 2000-264322 A has been proposed as a printer apparatus that uses this kind of heat-sensitive adhesive sheet.
According to the disclosed printer apparatus, after a thermoplastic adhesive layer is activated by a thermal activation device, desired characters, images, and the like can be printed on a printable surface of a heat-sensitive adhesive sheet by using a thermal printer apparatus. The heat-sensitive adhesive sheet can then cut into a predetermined length.
A display sheet is applied to a glass bottle used for alcoholic beverages or pharmaceuticals, to a plastic container, or the like, or a price label or an advertisement sheet is applied thereto, after adhesion develops in the thermoplastic adhesive sheet. Thus, there is an advantage in that costs can be reduced because release paper (liner) like that employed with conventional general adhesive label sheets is unnecessary. Further, the linerless label printer also has merit from the viewpoint of resource-saving and environmental protection because the release paper, which becomes waste after use, is not necessary.
However, with the conventional printer apparatus described above, the desired characters, images, and the like are printed onto the printable surface of the heat-sensitive adhesive sheet by the thermal printer apparatus after the heat-sensitive adhesive layer is activated by the thermal activation device.
The heat-sensitive adhesive sheet in which adhesion has developed is transported to the thermal printer apparatus. A problem thus exists in which paper jamming tends to occur because the heat-sensitive adhesive sheet adheres to a platen roller used for printing, and then winds around the platen roller.
Further, configuring surfaces of the platen roller used for printing by using a material having a relatively low surface energy substance as a main constituent, such as a silicone resin or a fluorine resin, to which the heat-sensitive adhesive sheet does not easily adhere, has been considered in order to make paper jam like that describe above less likely to occur. There is a problem, however, in that manufacturing costs are high.
Furthermore, the thermal activation device performs thermal activation with the printer apparatus described above, and the thermal printer apparatus prints the desired characters, images, and the like. The sheet is then cut into a desired length by using a cutter device. There is a danger that the heat-sensitive adhesive that has developed adhesion will adhere to a blade of the cutter device, lowering the cutting quality. With the printing apparatus described above, inactive areas of the heat-sensitive adhesive layer (that is, regions where heating processing is not performed by the thermal activation device, and where adhesion does not develop) are provided in a leading edge portion and a trailing edge portion that correspond to cutting positions of the heat-sensitive adhesive sheet. Adhering of the heat-sensitive adhesive on the blade of the cutter device in the cutting positions can thus be avoided.
However, the inactive areas where, as described above, the heat-sensitive adhesive layer is not active and where adhesion does not develop, remain in the leading edge portion and the trailing edge portion of the heat-sensitive adhesive sheet (label) that has been cut by the cutter device. There is a problem in that when applying the heat-sensitive adhesive sheet to an object the areas without adhesion easily peel.
Further, it is necessary to stop transporting the heat-sensitive adhesive sheet when performing cutting by the cutter device, and a thermal head of the thermal activation device has residual heat even after electric power is cut off. Accordingly, there is a danger that the heat-sensitive adhesive layer of the heat-sensitive adhesive sheet positioned in the thermal activation device will be activated and adhere to the thermal head, and there is a danger that heat will penetrate to the printable surface, resulting in unnecessary color development.